If you buy the card for $1 and list it for .90, the buyer will be paying 1.15. You would make .15, because you have already paid the shipping. COMC deposits the future shipping into your account

no, if you buy a card for $1.00 and list it for 0.90, whoever buys it gets it for 0.90 because you already paid the .25 shipping as part of the dollar...so you lose 10 cents. If you want to make anything, you list it for more than a buck.